People used to say something similar in games: 'Why write in C when you know you are going to have to move to asm anyway, just write it all in asm!'.
I've never seen more then 5% of c code usefully move to asm and I've never seen more then a few % of python code usefully move to a module. I am not saying it's always of waste of time it's just I haven't seen it.
Mainly in and around video games on PC/PS2/XBox/PS1. C/C++/ASM for the runtime (sometimes with python for scripting) and Python for level editing and build processes.
I'm not discounting python inadequacies esp when churning vast amounts of data. Video game levels are large and python was too slow to process collision maps, shadow maps etc but we added C modules to do the heavy work and it wasn't a lot of code to write in C (it was a pita to debug them though).
PS I don't work in video games any more so I've not experienced the delights of the PS3/XBox2 first hand. I do websites now... it's a lot easier :)
I've never seen more then 5% of c code usefully move to asm and I've never seen more then a few % of python code usefully move to a module. I am not saying it's always of waste of time it's just I haven't seen it.